Channel density in highly parallel free space optical interconnects

Free space optical interconnects (FSOIs) are widely discussed as a solution for communication bottlenecks of VLSI electronics. Besides the high temporal bandwidth of optical interconnects, the high degree of parallelism of free space optics is promising for providing the necessary channel density (number of channels per volume). The channel density represents an important figure of merit to characterize highly parallel FSOIs. In this thesis strategies for optimizing (maximizing) the number of channels at a given SNR are investigated. We identify the noise in FSOIs which originates from the (i) integral channel-to-channel crosstalk induced by light diffraction, divergence, and system misalignment, and (ii) the detector pre-amplifier thermal noise, as a critical parameter to determine the maximum number of channels of interconnect systems. Based on a FSOIs model system we have shown that this noise parameter can provide optimum design criteria for the detector size and the channel spacing at a desired SNR.;We also evaluate FSOIs based on a nondiffracting Bessel beams. Our evaluation is promoted by two goals. The first goal is to emphasize the importance of using the fill factor of the detector array as a design parameter to determine the optimum number of channels. Our analysis shows that the fill factor of source and detector arrays is a determining factor for the number of channels that can be realized. The side lobes of Bessel beams act as a major source of noise which severely limits the channel density. The second goal is to show that the integral channel-to-channel crosstalk for FSOIs using nondiffracting Bessel beams should be considered for performance evaluation and evaluating the system based on the crosstalk between two channels is inadequate.;Finally, the effect of two important second order parameters of the light sources on the channel density has been studied. The first parameter is the finite linewidth and the second parameter is the influence of higher order modes. We show that the effect of the source linewidth is small when a laser is used as the light source. The effect of the modes on the channel density is more pronounced and should be considered in the FSOIs design. (Abstract shortened by UMI.).